Zinc powder is only suitable for use in alkaline batteries if it exhibits a sufficiently low evolution of hydrogen gas in the electrolyte also without a current output. To this end, zinc powder is generally passivated by means of mercury. This passivation may be attained either by a so-called subsequent amalgamation following the powder preparation or by powdering zinc amalgams according to German Offenlegungsschrift 24 41 356.
However, the use of mercury involves considerable expense for labor and environmental protection. In the course of the preparation and handling of the zinc-mercury powder until charging same into the batteries, measures for environmental protection and labor protection are always necessary, since the mercury evaporates from the zinc powder. The relatively large surface of the zinc powder even causes the saturation vapor pressure of mercury above the zinc powder to be reached very rapidly.